Separable fastening device

ABSTRACT

A separable fastening device having first and second separable members wherein the first member has a surface of upstanding spear-like protuberances extending from one broad surface of its base and the second member has a surface of complementary engaging elements. The spear-like protuberances are characterized by the property that when the first and second separable fastener members are pressed into face-to-face relationship the spear-like protuberances on the first separable member penetrate the surface of the second separable member and engage the complementary engaging elements of the second separable member and resist separation parallel to the interfacial plane of engagement but are readily separable by peeling forces applied substantially normal to this interfacial plane. The first separable member having a surface of spear-like protuberances has particular utility as part of a separable fastener having reticulated urethane foam as the second complementary member, however it also provides a superior fastening device when used with a second separable member having a surface of complementary engaging elements in loop form.

United States. Patent 1 Ribich et a1.

[11] 3,708,833 [451 Jan. 9, 1973 [54] SEPARABLE FASTENING DEVICE [75] Inventors: William A. Ribich, Lexington; Charles Kojabashian, Sudbury, both of Mass; Lauret ll. Girard, Bedford, NH.

[73] Assignee: American Velcro, Inc., New York,

[22] Filed: March 15,197!

[21] Appl. No.: 124,066

[52] US. Cl ..24/204 [51] Int. Cl. ..A44b 17/00 [58] Field of Search ..24/204 [5 6] References Cited UNITED STATES PATENTS 3,494,006 2/1970 Brumlik ..24/204 3,522,637 8/1970 Brumlik... .....24/204 2,496,820 2/1950 Smith ..24/204 3,166,072 1/1965 Su1livan.... ..24/204 3,266,113 8/1966 Flanagan "24/204 FOREIGN PATENTS OR APPLICATIONS 1,140,576 1/1969 Great Britain ..24/204 Primary Examiner-Bernard A. Gelak Attorney-Fannie, Edmonds, Morton, Taylor & Adams [57] ABSTRACT A separable fastening device having first and second' separable members wherein the first member has a surface of upstanding spear-like protuberances extending from one broad surface -of its base and the second member has a surface of complementary engaging elements. The spear-like protuberances are characterized by the property that when the first and second separable fastener members are pressed into face-to-face relationship the spear-like protuberances on the first separable member penetrate the surface of the second separable member and engage the complementary engaging elements of the second separable member and resist separation parallel to the interfacial plane of engagement but are readily separable by peeling forces applied substantially normal to this interfacial plane. The first separable member having a surface of spear-like protuberances has particular utility as part of a separable fastener having reticulated urethane foam as the second complementary member, however it also provides a superior fastening device when used with a second separable member having a surface of complementary engaging elements inloop form.

21 Claims, 9 Drawing Figures PATENTED 9 I975 3,708,833

SHEET 1 OF 2 INVENTORS WILLIAM A. RIBICH CHARLES KOJ'ABASHIAN BY LAURENT H. GIRARD ATTORNEYS PATENTEDJAN 9 I975 SHEET 2 [IF 2 FIG. 5

. GIRARD INVENTORS WILLIAM A. RIBICH CHARLES KOJ'ABASHIAN TTOREYS SEPARABLE FASTENING DEVICE This invention relates to a separable fastening device and more particularly to a fastening device having complementary engaging surfaces which are releasably interengageable and resist separation parallel to the interfacial plane of engagement but are readily separable by peeling forces applied substantially normal to this plane. This invention provides an improvement in such fasteners which includes a first member characterized by a plurality of spear-like protuberances extending from one surface thereof and a second member having a complementary engaging surface. The second member may comprise an open cell foamed plastic member in which membranes have been removed from the foam structure to provide at least a partial skeletal structure of interconnected closed strands at the surface of the foam member for engagement with the spear-like protuberances upon placing the two members in face-to-face relationship.

Separable fasteners such as those described in US. Pat. Nos. 2,717,437 and 3,009,235 which are marketed under the registered trademark VELCRO brand hook and loop fasteners by Velcro Corporation, 681 Fifth Avenue, New York, NY. have gained wide acceptance because of the properties of the mating hooks and loops which permit their attachment by merely placing a surface defined by the hooks into face-to-face relationship with a surface defined by the loops so that a large number of hooks engage a large number of loops which resist separation parallel to the interfacial plane of engagement but are readily separable by peeling forces applied substantially normal to this interfacial plane. These fastening devices are generally formed of a sheet of woven fabric having raised threads of synthetic material, such as nylon, which are napped or unnapped, to provide a pile surface defined by a plurality of loops, and which may be thermally treated to become semi-rigid. Certain of the loops may then be cut along one side near their outer extremity to form hooks.

While these hooks provide excellent holding properties, we have discovered newly configured spear-like protuberances which offer improved engagement and holding properties especially when matedwith such reticulated foam. An earlier development mating the hooks of the hook and loop fastener with reticulated foam permitted limited engagement but lacked the quality of engagement realized by the invention.

One application showing the use of said hook and loop fasteners for attaching a gas cleaning filter to a frame is described in US. Pat. No. 3,127,259 to Boylan. Other prior art generally relating to the art of the invention includes: French Patent 1,131,934 which provides a joinder between short perpendicular fibers on one surface and foam on the other wherein the fibers penetrate into the foam so that the foam will become impaled on these fibers; U.S. Pat. No. 3,295,155 to Belsky et al. which relates to fibrous foam mop pads retained in place by prongs which have oppositely angled tip ends; US. Pat. No. 3,266,113 to Flanagan, Jr. which generally refers to fastening devices having complementary surfaces of articles which interengage each other to resist separation. None of these patents disclose concepts which are in any manner related to applicants invention of utilizing spear-like protuberances in combination with complementary engaging elements to form a separable fastener. Other prior art also includes US. Pat. Nos. 3,226,751 to Lemelson, 3,080,688 to Politzer, 2,991,843 to Bell, Jr., 3,005,219 to Miller, 3,094,330 to Smith, 3,302,232 to Wasiloff et al. and 3,171,820 to Volz.

Broadly stated, the invention relates to a separable fastening device having first and second separable members wherein the first member has a surface of upstanding engaging elements extending from one broad surface of its base and the second member has a surface of complementary engaging elements extending from one broad surface of its base which are releasably interengageable with the engaging elements of the first separable member when the members are pressed into face-to-face relationship. The invention particularly relates to improvements in the first separable member wherein certain of the upstanding engaging elements comprise flexible spear-like protuberances, each having a stem supported at one end thereof on the base of the first separable member. On the unsupported end of the stem is a flexible spear-like head having at least two opposite radial extensions which slope from the end of said stem toward the surface of the base and extend away from said stem and are resiliently flexible in a plane parallel to the plane of said stem. The spear-like protuberances are characterized by the property that when the first and second separable fastener members are pressed into face-to-face relationship the spear-like protuberances on the first separable member penetrate the surface of the second separable member and engage the complementary engaging elements of the second separable member and resist separation parallel to the interfacial plane of engagement but are readily separable by peeling forces applied substantially normal to this interfacial plane.

The invention is particularly compatible with foam as the secondary complementary member. In a preferred embodiment the second complementary member comprises reticulated urethane foam having a three dimensional partial skeletal structure of strands at the surface of the foam plastic member.

In addition the invention can be used directly with end use products such as those used as filter media in air conditioning units and in other acoustical and hygienic filtering applications. These uses comprise important applications of the fastening device of the invention. By framing or partially framing the opening in which the open cell filter media is to be placed, a filter having the foam surface described can easily be attached in place and removed for cleaning or replacement by simply pressing the foam member in contact with the spear-like elements. Thus, the method of securing members incorporating a foamed plastic surface as described with the member having spear-like protuberances also forms a part of this invention.

Further uses of the fastening device include attaching foam backed carpeting to the floor, the use of foam as gasket material, the attachment of foam protector mats or pads such as in athletic uses, the holding of foam-type insulation in place, and the attachment of foam sponges and the like to devices for washing cars, dishes and the like. The fastener could also be used in fabricating foam products of different types where the spear-like protuberances can be used for interim holding of the foam during some treatment or operation on the foam. In addition, the spear-like protuberances have been found to replace the hooks in hook and loop 1 fasteners whereby a first member having on one surface a plurality of spear-like protuberances of the instant invention is pressed in face-to-face relationship with a second member having on one surface a plurality of loop elements. The spear-like protuberances deeply penetrate the loops of the second surface and a large number of spear-like engaging elements engage onto a large number of loop elements to form a fastening device of superior holding power as contrasted to the fastening devices of the prior art.

A preferred embodiment of the invention is described with reference to the drawings wherein:

FIG. 1 is a perspective view of an open cell foamed plastic member partially in face-to-face relationship with a surface of spear-like protuberances;

FIG. 2 is a perspective view of the spear-like protuberance of the present invention;

FIG. 3 is a front elevational view of the spear-like protuberance of FIG. 2;

FIG. 4 is a side elevational view of the spear-like protuberance of FIG. 2;

FIG. 5 is a perspective view of an alternate embodiment of the spear-like protuberance;

FIG. 6 is a front elevational view of the spear-like protuberance of FIG. 5;

FIG. 7 is a side elevational view of the spear-like protuberance of FIG. 5;

FIG. 8 is a greatly enlarged fragmentary view of the attachment of a surface of spear-like protuberances to an open cell foamed plastic member taken substantially along lines 8-8 of FIG. 1, illustrating the use of both embodiments of the spear-like protuberances of the invention; and

FIG. 9 is a greatly enlarged fragmentary view of the attachment of a surface of spear-like protuberances to a member having a complementary surface of loops, illustrating the use of both embodiments of the spearlike protuberances of the invention.

In the following description of the spear-like protuberances of the first separable member, downward and lower refer to the direction toward the base of the separable member and upward" and upper refer to the direction toward the unsupported end of the protuberance. Forward" or face" refers to the front portion of the protuberance which is configured of variously sloped surfaces as shown in FIGS.'2-3 and FIGS. 5-6 and rearward or rear" refers to the opposite portion behind the face portion of the protuberance. v

The spear-like protuberances of the instant invention which may be a plastic material for example, are shown clearly in FIG. 2 and FIG. 5. They are preferably affixed to a flexible base as for example, plastic. The protuberances may be more flexible than the base to facilitate resilient interengagement and disengagement with the complementary engaging elements of the second separable member.

The protuberance 10 shown in FIG. 2 is comprised of a stem 12, preferably tapered as shown, having a head 14 at the unsupported end of the stem 12. The head 14 utilizes a double eye" structure and is comprised of at least two ears or radial extensions 16 which preferably slope from the unsupported end of the stem 12 downward toward the base 32 of the first separable member. The radial extensions 16 extend away from the stem 12 such that the free end represented by surface 17 of each extension 16 is in spaced relationship with the side surfaces of the stem. The configuration of the radial extensions 16 as shown in FIGS. 2-4 and FIGS. 5-7 provide improved engaging capability of the spear-like protuberances with the complementary engaging elements of the second complementary surface of the fastening device.

The tapered stem 12 is preferably configured of five flat surfaces as shown, which define in cross-section a five sided polygon. A rear surface 11 extends perpendicularly from the base 32 to the unsupported endmost portion of the protuberanceflTwo side surfaces 30 of the stem 12 which taper from the base 32 toward the head 14 extend longitudinally along each side of the stem and curve continuously and smoothly into and throughout each radial extension to define a rounded concave configuration 28 and continue to define the sloping lower surfaces 26 of the radial extensions 16. The sloping lower surfaces 26 also are preferably configured to have an angled relationship with respect to the downward sloping upper surfaces 22 of the radial extensions 16. v

The forward portion or face of the stem 12 is defined by two symmetrical and oppositely angled surfaces 13, which extend longitudinally along said forward portion and define the configuration of the face of the stem 12. The surfaces 13 curve continuously and smoothly throughout each of said radial extensions 16 defining the forward or face surfaces 15 of each radial extension In the preferred embodiment the free ends of the radial extensions are configured as flat surfaces 17 which are preferably sloped toward the stem 12 and extend from the lower surface 26 to the upper surface 22 of the radial extensions 16. This facilitates maximum penetration of the protuberances into the complementary engaging surface of the second separable member.

To increase the penetrating capability and thus provide maximum engagement of the protuberances with the complementary engaging elements at or near the surface of the second separable member, a sharp pointed apex 18 is preferably provided at the top of the stem 12 to define a relatively pointed structure. The sloping side surfaces 24 of the pointed apex 18 extend downward to join the sloping upper surfaces 22 of the radial extensions 16 at a smooth concave recess 20. The concave recess 20 provides maximum resilient flexibility for the radial extensions 16 of the spear-like head 14. A flat sloping surface 19 which improves the penetrating capability of the protuberance 10 by providing an improved sharp configuration for penetration of the apex 18, is also provided in the preferred configuration.

The specific configuration comprising the smooth blended contours and the sloping surfaces described facilitates maximum resilient and repeated engagement of the protuberances 10, which are preferably molded integrally with the base 32 of a resilient material as for example plastic, with the complementary engaging elements of the opposite surface of the fastening device. An example of such molding is described in us. Pat.

application of Menzin et al., Ser. No. 824,597 which is assigned to the same assignee as the present application.

This repeated engagement is due to the resilient bending of the radial extensions 16 in a plane parallel to the plane of the stems 12 due to this configuration. The flexible characteristics of the protuberances in combination with the unique configuration thereof shown and described in the preferred embodiment, provide superior engaging capabilities with loop elements 50 shown in FIG. 9 or the foamed plastic structure 52 shown in FIG. 1 and FIG. 8.

FIGS. 5-7 illustrate an alternate embodiment of the spear-like protuberance heretofore described with the exception of the apex 18 provided at the top of the protuberance shown in FIGS. 2-4. The spear-like protuberance shown in FIG. 7 includes a concave recess 36 at the top of the stem 34 where the upper surfaces 38 of the radial extensions 40 join to form a smooth concave surface which provides maximum resilient flexibility for the radial extensions 40 of the spear-like head 42. The flexible characteristics of the protuberance 44 shown in FIGS. 5-7, which is preferably of plastic material molded integrally with the base 46, in'combination with the concave junctions 48 and the concave recess 36, provide resilient flexibility which facilitates maximum repeated engagement and maximum holding power of the protuberances with the complementary engaging surface of the opposite engaging member of the fastening device.

An application of the fastening device of the invention (not shown) utilizes a tape which frames the air passageway of an air conditioning unit. The tape comprises a base member having upstanding spear-like protuberances as in the manner disclosed herein. The

base member can be coated on its back with a pressure sensitive adhesive to facilitate attachment of the tape member to the cabinet of the air conditioning unit. A foamed plastic sheet which is to be used as the filter in the air conditioning unit is, in this embodiment, a sheet of controlled pore reticulated foam consisting of low I density urethanes and is characterized by a threedimensional skeletal structure of strands which can provide 97 percent or more of void space since it is substantially devoid of membranes; foam of this type is described in US. Pat. No. 3,17 l ,820 to Volz. By merely pressing the foam surface in contact with the surface of the tape member defined by the spear-like protuberances, a large number of radial extensions of the protuberances will attach to the interconnected strands of the foam and upon release of the pressure required to interconnect the engaging elements the foam will return to its former shape and retain its high degree of permeability. Reticulated foams of this type are relatively strong, have good fatigue resistance and tear abrasion, and thus when engaged will resist separation parallel to the interfacial plane of engagement but are readily separable from the tape member by peeling forces applied substantially normal to this interfacial plane. Once the foamed plastic filter has been attached in this manner it may be retained in position to function as an effective filter medium in the air conditioning unit.

Although reticulated foams'are preferred since they present the maximum number of strands at the surface of the foam sheet for engagement by the hooks, other open cell foams which might have a small percentage of membranes still intact but present a sufficient number of interconnected strands at the surface for engagement with the spear-like protuberances can also be used in the fastening device of the invention.

While an application of the invention has been described in relation to an open cell foam which may be used as a filter media the open cell foam could itself be in the form of a tape member or could be laminated to other foams in open cell or any other member for specific fastening requirements.

We claim:

1. In a separable fastening device having first and second separable members wherein the first member has a surface of upstanding engaging elements extending from one broad surface of its base and the second member has a surface of complementary engaging ele-- ments extending from one broad surface of its base which are releasably interengageable with the engaging elements of the first separable member, the improvement inthe first separable member comprising certain of said upstanding engaging elements being flexible spear-like protuberances, each having:

a. a resilient stem supported at one end thereof on the base of the first separable member; a flexible spear-like head on the unsupported end of said stern, said head having at least two radial extensions which slope from the end of said stem toward the surface of the base and extend away from said stern and are resiliently flexible relative to said stem, a portion of each radial extension being of smaller thickness adjacent to said stem than a corresponding portion along said radial extension closer to the unsupportedend, said spearlike protuberances characterized by the property that when the first and second separable fastener members are pressed into face-to-face relationship the spear-like protuberances on the first separable member penetrate the surface of the second separable member and engage the complementary engaging elements of the second separable member and resist separation parallel to the interfacial plane of engagement but are readily separable due to the mechanical flexing cooperation of said radial extensions with said stem by peeling forces applied substantially normal to this interfacial plane in all directions relative to the lengthwise and widthwise dimensions of said separable fastener members.

2'. Separable fastening device according to claim 1 wherein the configuration of said spear-like protuberances further comprises a concave recess at the unsupported endmost portion of said stem where the sloping upper surfaces of said radial extensions of said spearlike head join with the end of said stem, and a rounded concave configuration on theradial extensions where the sloping lower surfaces of said radial extensions joins with the side surfaces of said stem, said concave recess and configurations mechanically cooperating to facilitate resilient bending of said radial extensions relative to said stem in a plane parallel to the plane of said stern.

Y 3. Separable fastening device according to claim 2 wherein said base material is flexible to facilitate peeling said first separable member from the second separable member.

4. Separable fastening device according to claim 3 wherein said spear-like protuberances are more flexible than said base to facilitate repeated resilient in-' terengagement of said spear-like protuberances with the complementary engaging elements of the second separable member.

5. Separable fastening device according to claim 2 wherein said first member comprises a molded plastic material.

6. Separable fastening device according to claim 5 wherein each stem of said spear-like protuberances tapers from the base toward said head.

7. Separable fastening device according to claim 6 wherein the spear-like protuberances extend substantially perpendicular to the base of the first separable member.

8. Separable fastening device according to claim 7 wherein the second separable member has one surface defined by an open cell foamed plastic in which membranes have been removed to provide at least a partial skeletal structure of interconnected closed strands at the surface thereof, the separable members joined in face-to-face relationship with said spear-like protuberances on the first separable member extending into but not through the second separable member and a large number of spear-like protuberances releasably engaging onto a large number of strands at or near the surface of the second separable member.

9. Separable fastening device according to claim 8 wherein the foamed plastic is reticulated urethane foam having a three dimensional skeletal structure of strands.

10. Separable fastening device according to claim 7 wherein the second separable member has a surface of complementary engaging elements in loop form.

11. Separable fastening device according to claim 7 wherein the tapered stem of each spear-like protuberance is defined by five fiat surfaces defining in crosssection a five sided polygon said surfaces including:

a. a surface defining the rear portion of said protuberance, extending from the base to the endmost portion thereof, and substantially perpendicular to said base;

b. a surface on each side of said stem tapering from the base toward said head and extending longitudinally along each side of said stem and curving continuously and smoothly into and throughout each of said radial extensions to define said rounded concave configuration and sloping lower surfaces of said radial extensions, said downward sloping lower surfaces further having an angled relationship with the downward sloping upper surfaces of said radial extensions; and

c. two flat surfaces defining the forward configuration of said stern, said surfaces having a symmetrical relationshipv with said stem and oppositely angled with respect to each other, extending longitudinally along the forward portion of said stem and curving continuously and smoothly throughout each of said radial extensions defining the forward surfaces thereof, said configuration facilitating resilient bending of said radial extensions relative to said stem in a plane parallel to the plane of said stem.

12. Separable fastening device according to claim 1 1 wherein the free end of each of said radial extensions is defined by a flat surface which slopes toward the endmost portion of said stem and extends from the lower sloping surface to the upper sloping surface of said radial extensions, said configuration facilitating improved penetration of said spear-like protuberances of said first separable member into the complementary engaging surface of the second separable member.

13. Separable fastening device according to claim 7 further including a sharp pointed apex at the top unsupported end of said stem of each protuberance, said apex facilitating improved penetration of the spear-like protuberances of the first separable member into the complementary engaging surface of the second separable member.

l4. Separable fastening device according to claim 13 wherein the side surfaces defining said apex are configured to join with the downward sloping upper surfaces of the adjacent radial extensions of said spear-like head by a continuously curved configuration, the configuration also including a concave recess on each side of said apex to provide resilient bending flexibility to said radial extensions relative to each stem to permit resilient bending in a plane parallel to the plane of said stem.

15. Separable fastening device according to claim 14 wherein the second separable member has one-surface defined by an open cell foamed plastic in which membranes have been removed to provide at least a partial skeletal structure of interconnected closed strands at the surface thereof, the separable members joined in face-to-face relationship with said spear-like protuberances on the first separable member extending into but not through the second separable member and a large number of spear-like protuberances releasably engaging onto a larger number of strands at or near the surface of the second separable member.

16. Separable fastening device according to claim 15 wherein the foamed plastic is reticulated urethane foam having a three dimensional skeletal structure of strands. v

17. Separable fastening device according to claim 14 wherein the second separable member has a surface of complementary engaging elements in loop form.

18. Separable fastening device according to claim 14 wherein the free end of each of said radial extensions is defined by a flat surface which slopes toward the endmost portion of said stem and extends from the lower sloping surface to the upper sloping surface of said radial extensions, and the forward portion of said pointed apex is defined by a flat surface which slopes toward the rear of said spear-like protuberance and extends from the base of said apex to the tip, said configuration facilitating improved penetration of said spearlike protuberances of the first separable member into the complementary engaging surface of the second separable member.

19. Separable fastening device according to claim 18 wherein the tapered stem of each spear-like protuberance is defined by five flat surfaces defining in crosssection a five sided polygon said surfaces including:

a. a surface defining the rear portion of said protuberance, extending from the base to the endmost portion thereof, and substantially perpendicular to said base;

b. a surface on each side of said stem tapering from the base toward said head and extending longitudinally along each side of said stem and curving continuously and smoothly into and throughout each of said radial extensions to define said rounded concave configuration and sloping lower surfaces of said radial extensions, said downward sloping lower surfaces further having an angled relationship with the downward sloping upper surfaces of said radial extensions; and

c. two flat surfaces defining the forward configuration of said stem, said surfaces having a symmetrical relationship with said stem and oppositely angled with respect to each other, extending longitudinally along the forward portion of said stem and curving continuously and smoothly throughout each of said radial extensions defining the forward surfaces thereof, said configuration facilitating resilient bending of said radial extensions relative to said stem in a plane parallel to the plane of said stem 20. Separable fastening device according to claim 1 wherein the second separable member has at least one surface defined by an open cell foamed plastic in which membranes have been removed to provide at least a partial skeletal structure of interconnected strands at the surface thereof such that when the separable members are joined in face-to-face relationship the spearlike protuberances of the first separable member extend into but not through the second separable member and a large number of spear-like protuberances engage onto a large number of strands at or near the surface of the second separable member.

21. Separable fastening device according to claim 20 wherein the foamed plastic is reticulated urethane foam having a three dimensional skeletal structure of strands. 

2. Separable fastening device according to claim 1 wherein the configuration of said spear-like protuberances further comprises a concave recess at the unsupported endmost portion of said stem where the sloping upper surfaces of said radial extensions of said spear-like head join with the end of said stem, and a rounded concave configuration on the radial extensions where the sloping lower surfaces of said radial extensions joins with the side surfaces of said stem, said concave recess and configurations mechanically cooperating to facilitate resilient bending of said radial extensions relative to said stem in a plane parallel to the plane of said stem.
 3. Separable fastening device according to claim 2 wherein said base material is flexible to facilitate peeling said first separable member from the second separable member.
 4. Separable fastening device according to claim 3 wherein said spear-like protuberances are more flexible than said base to facilitate repeated resilient interengagement of said spear-like protuberances with the complementary engaging elements of the second separable member.
 5. Separable fastening device according to claim 2 wherein said first member comprises a molded plastic material.
 6. Separable fastening device according to claim 5 wherein each stem of said spear-like protuberances tapers from the base toward said head.
 7. Separable fastening device according to claim 6 wherein the spear-like protuberances extend substantially perpendicular to the base of the first separable member.
 8. Separable fastening device according to claim 7 wherein the second separable member has one surface defined by an open cell foamed plastic in which membranes have been removed to provide at least a partial skeletal structure of interconnected closed strands at the surface thereof, the separable members joined in face-to-face relationship with said spear-like protuberances on the first separable member extending into but not through the second separable member and a large number of spear-like protuberances releasably engaging onto a large number of strands at or near the surface of the second separable member.
 9. Separable fastening device according to claim 8 wherein the foamed plastic is reticulated urethane foam having a three dimensional skeletal structure of strands.
 10. Separable fastening device according to claim 7 wherein the second separable member has a surface of complementary engaging elements in loop form.
 11. Separable fastening device according to claim 7 wherein the tapered stem of each spear-like protuberance is defined by five flat surfaces defining in cross-section a five sided polygon said surfaces including: a. a surface defining the rear portion of said protuberance, extending from the base to the endmost portion thereof, and substantially perpendicular to said base; b. a surface on each side of said stem tapering from the base toward said head and extending longitudinally along each side of said stem and curving contInuously and smoothly into and throughout each of said radial extensions to define said rounded concave configuration and sloping lower surfaces of said radial extensions, said downward sloping lower surfaces further having an angled relationship with the downward sloping upper surfaces of said radial extensions; and c. two flat surfaces defining the forward configuration of said stem, said surfaces having a symmetrical relationship with said stem and oppositely angled with respect to each other, extending longitudinally along the forward portion of said stem and curving continuously and smoothly throughout each of said radial extensions defining the forward surfaces thereof, said configuration facilitating resilient bending of said radial extensions relative to said stem in a plane parallel to the plane of said stem.
 12. Separable fastening device according to claim 11 wherein the free end of each of said radial extensions is defined by a flat surface which slopes toward the endmost portion of said stem and extends from the lower sloping surface to the upper sloping surface of said radial extensions, said configuration facilitating improved penetration of said spear-like protuberances of said first separable member into the complementary engaging surface of the second separable member.
 13. Separable fastening device according to claim 7 further including a sharp pointed apex at the top unsupported end of said stem of each protuberance, said apex facilitating improved penetration of the spear-like protuberances of the first separable member into the complementary engaging surface of the second separable member.
 14. Separable fastening device according to claim 13 wherein the side surfaces defining said apex are configured to join with the downward sloping upper surfaces of the adjacent radial extensions of said spear-like head by a continuously curved configuration, the configuration also including a concave recess on each side of said apex to provide resilient bending flexibility to said radial extensions relative to each stem to permit resilient bending in a plane parallel to the plane of said stem.
 15. Separable fastening device according to claim 14 wherein the second separable member has one surface defined by an open cell foamed plastic in which membranes have been removed to provide at least a partial skeletal structure of interconnected closed strands at the surface thereof, the separable members joined in face-to-face relationship with said spear-like protuberances on the first separable member extending into but not through the second separable member and a large number of spear-like protuberances releasably engaging onto a larger number of strands at or near the surface of the second separable member.
 16. Separable fastening device according to claim 15 wherein the foamed plastic is reticulated urethane foam having a three dimensional skeletal structure of strands.
 17. Separable fastening device according to claim 14 wherein the second separable member has a surface of complementary engaging elements in loop form.
 18. Separable fastening device according to claim 14 wherein the free end of each of said radial extensions is defined by a flat surface which slopes toward the endmost portion of said stem and extends from the lower sloping surface to the upper sloping surface of said radial extensions, and the forward portion of said pointed apex is defined by a flat surface which slopes toward the rear of said spear-like protuberance and extends from the base of said apex to the tip, said configuration facilitating improved penetration of said spear-like protuberances of the first separable member into the complementary engaging surface of the second separable member.
 19. Separable fastening device according to claim 18 wherein the tapered stem of each spear-like protuberance is defined by five flat surfaces defining in cross-section a five sided polygon said surfaces including: a. a surface defining the rear portion of said protuberaNce, extending from the base to the endmost portion thereof, and substantially perpendicular to said base; b. a surface on each side of said stem tapering from the base toward said head and extending longitudinally along each side of said stem and curving continuously and smoothly into and throughout each of said radial extensions to define said rounded concave configuration and sloping lower surfaces of said radial extensions, said downward sloping lower surfaces further having an angled relationship with the downward sloping upper surfaces of said radial extensions; and c. two flat surfaces defining the forward configuration of said stem, said surfaces having a symmetrical relationship with said stem and oppositely angled with respect to each other, extending longitudinally along the forward portion of said stem and curving continuously and smoothly throughout each of said radial extensions defining the forward surfaces thereof, said configuration facilitating resilient bending of said radial extensions relative to said stem in a plane parallel to the plane of said stem.
 20. Separable fastening device according to claim 1 wherein the second separable member has at least one surface defined by an open cell foamed plastic in which membranes have been removed to provide at least a partial skeletal structure of interconnected strands at the surface thereof such that when the separable members are joined in face-to-face relationship the spear-like protuberances of the first separable member extend into but not through the second separable member and a large number of spear-like protuberances engage onto a large number of strands at or near the surface of the second separable member.
 21. Separable fastening device according to claim 20 wherein the foamed plastic is reticulated urethane foam having a three dimensional skeletal structure of strands. 